1. Field of the Invention
The present invention relates to an amine catalyst for producing flexible, semi-rigid, and rigid polyurethane, or elastomer and the like of polyurethane. More particularly, the present invention relates to an amine catalyst which has a secondary hydroxyl group in the molecule and is non-bleeding in the polyurethane resin and excellent in moldability, to a process for the production of polyurethane using the catalyst and a polyurethane.
2. Discussion of the Background
Polyurethane foam, is usually produced from a polyol and a polyisocyanate containing catalyst, foaming agent (halogenated hydrocarbon and/or water), and if necessary, other auxiliary agents by instantaneously stirring and mixing them to promote foaming.
Polyurethane foam is advantageously used as a material for various articles because of its light weight and excellence in cushioning property, anti-shock property, anti-vibration property, as well as other properties. Hitherto, as a catalyst for producing these polyurethanes, amine catalysts such as triethylamine, N-ethylmorpholine, triethylenediamine, tetramethylhexamethylenediamine, and the like have been employed to achieve good moldability of the foams. However, it is known that the use of these amine catalysts brings about various further problems when the catalysts are used in production. For example, when producing interior articles of automobiles such as instrument panels, seats, head rests, arm rests, and the like which are produced from polyurethane foam together with other materials such as, for example, polyvinylcholoride resin, ABS resin, polycarbonate resin, and the like, either in a combined form such as foil, coating, and border materials, or by being molded integratedly, with these materials, problems arise due to the interaction between the amine catalyst and the other materials. For example, an amine catalyst remaining in a polyurethane foam may migrate onto other materials in contact with the polyurethane foam to cause deterioration and discoloration of the other materials, and a reduction in the commercial value of the product.
So far, as solutions for these problems, the following processes have been proposed: a process employing an amine catalyst which has a reactive primary amino group or secondary amino group in the molecule (Japanese Laid-Open Patent Application No. Sho 46-4846, Japanese Laid-Open Patent Application No. Sho 59-191743, Japanese Patent Publication No. Sho 61-31727); a process employing an amine catalyst which contains a reactive primary hydroxyl group in the molecule (Japanese Patent Publication No. Sho 57-14762); and the like. These amine catalysts work to accelerate the formation reaction of a polyurethane foam, and at the same time react with the raw material polyisocyanate due to the presence of the reactive groups in the molecule and are incorporated into the polyurethane resin. Therefore, problems with the deteriorated physical property and discoloration of the resultant products can be avoided because the amine catalyst does not migrate to other materials in contact with polyurethane foam. But the amine catalysts having these reactive groups which are entrapped in the polyurethane resin lose their catalytic activity during the reaction, resulting in incomplete formation of the polyurethane resin. Thus, the problems of an increased percentage of rejected products having voids in the polyurethane foam and deteriorated moldability have been reported.
For production of an article from polyurethane foam either in combination with or molded integratedly with other materials, amine catalysts are desired which are non-bleeding so as not to deteriorate nor discolor the other materials which are brought into contact with the catalyst and, in addition, which are excellent in the moldability.
The present inventors continued comprehensive investigations on the amine catalyst for producing polyurethane and the method of production thereof.
As the result, the present inventors have found that an amine catalyst having a secondary hydroxyl group in the molecule shows non-bleeding in polyurethane resin, improved catalytic activity during the formation reaction of polyurethane, and does not deteriorate nor discolor other material contacting polyurethane roam when the catalyst is used for those products which are made from polyurethane foam by combining or molded integratedly with other material, and have completed the present invention.